The present invention relates generally to motor control systems and more particularly to a motor control system which permits customized modes of operation to satisfy individual needs.
It is well known in the art to provide motor control systems which respond to various motor operating parameters, such as current, voltage and speed, to control the voltage and/or current supplied to the motor and hence control the motor operation. (In the case of alternating current (a.c.) motors, the frequency of the power supplied to the motor is a further known control parameter.) For example, it may be desired, when starting a motor, to first control the voltage supplied to the motor as a function of its terminal voltage and subsequently, after the motor attains a predetermined speed, to control the applied voltage as a function of its actual speed. Similarly, in a jogging operation it may be desirable to control the motor solely as a function of its terminal voltage or the motor current.
These functions of motor control are normally achieved by what is commonly called a sequencing means or sequencer which responds to requesting inputs from an external source, such as an operator panel or input from an automated control system, to select the proper motor operating parameter to be used.
The sequencer itself is customarily comprised of logic means such as fixed logic circuitry or a programmed microprocessor to provide predetermined outputs in response to the requesting inputs. The problem here involved is that if a deviation from the normal sequencer operation is desired in order to meet some special or customized need, the sequencer must be physically modified. For example, if fixed logic circuitry is employed, the circuitry must be rewired. If a microprocessor is used and, as is common, the sequencing logic is found in a programmable read only memory (PROM) then the PROM must be replaced. This, obviously, results in greater expense since there is a deviation from the "standard" and it also does not allow for readily changing the overall system of operation.